Flashcards
DT A2 Materials and Testing
Flashcards do conjunto (28)
- 1What things do we bear in mind when choosing a material for a product?1. Primary one is its function ( solution to the need) - e.g. the need to drink - the material must be able to hold liquid.
2. Then consumer preference, manufacturing, safety , cost , life expectancy etc. will all be considered second - 2What does consumer preference refer to?The shape and form of the product and other aesthetic qualities such as colour and finish
- 3Why is it necessary to test materials ?Designer must know its suitable for its intended purpose - sufficient strength, toughness
- 4What is recorded when materials are tested using industrial methods?Results recorded on certificates stating their specific properties as numeric values
- 5What is destructive testing ?A range of tests that result in the destruction of a standard size and shape test piece.
Eg Hardness test pieces will have indentations and impact testing will cause it to bend or break.
The same can be done for products to test for durability - e.g. tyres to establish wear rates - 6What is hardness?The ability of a material to resist abrasive wear, indentation or deformation.
It is a by-product of strength - 7What are the 3 basic hardness tests ?Brinell
Vickers
Rockwell
Different scales are used depending on the material - 8What is the Brinell Test?A hardened steel ball forced into the surface by means of a suitable load.
The surface area of indent is measured by microscope - used to calculate hardness number - 9What is the Vickers Test?A diamond pyramid to cause an indent - measured using a microscope
- 10What is the Rockwell Test?Used for quality control of finished products.
Hardness value shown on a dial. - 11What is tensile testing ?Putting material under tension by stretching to provide information on tensile strength,elasticity,ductility and malleability
- 12Explain how to do a tensile test?A standard piece held between two grips
One grip is fixed, the other is attached to a vertical slide operated by an electric motor - then pulled out under tension until either it breaks or reaches limit of the machine.
The distance the vertical slide travels is recorded and plotted against the load applied which is sensed by a load transduce fixed to the moving grip - 13Give examples of industries that use tensile testingRubber, Steel and fabric in tyre industry, rope, clothing
- 14What do impact tests do?Test the toughness of a material and its resistance to shock.
A brittleness is often not revealed by tensile strength - 15Name 3 tests for impactIzod, Charpy, Houndsfield
- 16What is a Wear resistance TestRubbing with an abrasive.
E.g. weighing a disc of material ( e.g. brake discs) and rubbing an abrasive disc against it a specific number of times at a given pressure and then reweighing it to give a quantitative measure of wear.
Also used in crockery industry - 17What is Fatigue testing?Materials and products are tested for fatigue.
E.g. wire used in tyres is tested by gripping between two chucks one is stationery whilst the other rotates for a number of revolutions in both directions until a sample breaks.
Chairs - a weight is applied repeatedly to a product - 18What is Non destructive testing?Normally used on final product for surface or near surface flaws
Sometimes sophisticated equipment is required - welded joints and castings are tested this way - 19Name 4 non destructive tests1. Surface crack detection
2. Magnetic testing
3. Acid pickling
4. Internal defect detection - 20What is surface crack detection?Using sound (ringing for pottery and bell casting) and touch to sense faults.
Using a liquid penetrant - sprayed onto the surface stays in any cracks - helped by applying white chalk to make it more obvious - 21What is magnetic testing?Material is magnetised by making it part of an electromagnetic circuit.
Iron particles are dusted over the area and these show where magnetic forces are broken by a defect - useful for finding defects just below the surface - 22What is acid pickling?Cleaning a product so cracks can be seen in steel castings - weak sulphuric acid at 50 degrees - washes away the oxides
- 23Name 4 types of internal defect detection methodsLight
X-ray
Gamma ray
Ultrasonic testing - 24What is Light testing?Fine bone china use light to see through it
- 25What is X ray testingtyre industry check for air bubbles between layers of rubber
- 26What is Gamma ray testingSame method as x ray but used in cast iron and steel as gamma rays are harder and can detect air pockets in the casting
- 27Dangers with gamma ray testing and precautionsLethal to human tissue so testing takes places behind lead lined concrete walls and wear a photographic film badge which is monitored for exposure
- 28ultrasonic testingvery high frequency sound vibrations used to locate defects precisely.
Probe is passed over the components - used to test sheet, plate and strip metals and used in tyre, aircraft and pipeline inspections
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- A-Level DT A Level FlashCards sobre DT A2 Materials and Testing, criado por Joanne stibbard Kinsey em 02-03-2016.
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- Joanne stibbard Kinsey
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